The use of portable radio transmitting and receiving equipment is now commonplace. Some such equipments particularly cellular telephones, require an attached antenna.
When a cellular telephone is utilized inside an automotive vehicle, it is necessary that the antenna be supported on the exterior of the vehicle. If the antenna is placed inside the vehicle, it becomes ineffective, because the radio transmission is incapable of penetrating to the interior of the vehicle.
It has therefore been a practice to mount a fixed antenna on the exterior of a vehicle, when the vehicle is to be used for transporting a cellular telephone or other similar communication equipment.